Composition comprising polyethylene and an nu-oleyladipamide



United States Patent 2,991,263 COMPOSITION COMPRISING POLYETHYLENE ANDAN N-OLEYLADIPAMIDE Clayton F. Clark, Saxonville, Mass, and Robert W.Hill,

Leawood, Kans., assignors to Spencer Chemical Company, Kansas City, Mo.,a corporation of Missouri No Drawing. Original application June 18,1958, Ser. No. 742,755. Divided and this application Sept. 14, 1960,Ser. No. 55,835

3 Claims. (Cl. Mil-32.6)

This invention relates to plastic compositions and, more specifically,to novel polyethylenes of enhanced slip characteristics.

This application is a divisional of our copending application Serial No.742,755, filed June 18, 1858.

Polyethylene is one of the most popular and well known thermoplastics ofthis plastic age. The number of varied uses increases spectacularly eachyear; many of these include the utilization of polyethylene films.Polyethylene film is being used to package a wide and varied list ofcommercial commodities such as foods, meats, chemicals, pharmaceuticals,seeds, clothing, hardware, toys, etc. One of the more importantproperties associated with polyethylene fihn is its slip or film-to-fihncoeiiicient of friction. Slip, as it is known to the trade, relates tothe resistance of the film to a sliding action over another film surfaceor over a metal surface, as manifested by the thin sheets of blown filmsticking to one another. Poor Slip characteristics of polyethylene filmare especially troublesome to users of automatic packaging equipment.Poor slip is a greater problem with blown film, which is usually thinnerthan extruded sheets, although there are also many applications ofsheets in which an improved slip is also advantageous.

The object of this invention is to provide plastic compositions havingan improved slip or low film-to-film coefficient of friction. A furtherobject of this invention is to provide polyethylene compositions which,upon conversion to sheets or fihns, have an improved slip. A stillfurther object of this invention is to provide polyethylene films orsheets possessing improved slip characteristics.

There is provided by this invention novel plastic compositionscomprising polyethylene containing a small amount of an additive whichenhances the slip of the polyethylene. Additives which have been foundto enhance or improve the slip of polyethylene when incorporated thereinare the N-mono-oleyl and N,N'-dioleyl derivatives of dibasic aciddiamides, and particularly the compounds N,N'-dioleyladipamide andN-mono-oleyladipamide.

Additives of the described types are solids at room temperature,insoluble in water and soluble in most hot hydrocarbons. These compoundsare readily prepared by conventional processes such as by heating theappropriate fatty acid with the appropriate amine at about 230 C. forabout 0.5 to 1 hour under an atmosphere of nitrogen. The product isrecovered from the reaction mixture by the usual procedures.

The incorporation of a small amount of one or more of the describedadditives in polyethylene greatly reduces the polyethylene coefficientof friction. Polyethylene films and sheets and other products made frompolyethylene containing a small amount of an additive possess improvedslip characteristics.

ICC

Incorporation of the additive in the polyethylene may be efiected byseveral different methods. For example, the additive may be added as asolid, in solution or in the form of a slurry to polyethylene in eitherthe molding powder or pellet form followed by tumbling and drying. Theadditive may also be incorporated by melt blending the ingredients in aconventional apparatus, such as a Banbury mixer, heated rolls or aplasticater.

Additives of the described types are effective slip agents whenincorporated in polyethylene to give a polyethylene compositioncontaining about 0.01% to about l'%-by weight of the additive. Thepreferred composition is about 0. 05% to about 0.2% by weight ofadditive in polyethylene. Although more than 1% of additive may beincorporated in polyethylene, larger amounts would not generally bewarranted.

It is to be understood that minor amounts of other desirable materials,such as high melting waxes, antioxidants, dyes and pigments, lubricants,antistatic agents, and the like, may also be present in amounts which donot aifect the high slip properties of these polyethylene compositions,

The described additives are effective in improving the slipcharacteristics of all types of polyethylene, whether they be the morelinear polyethylenes prepared by the low pressure process, theconventional high pressure process polyethylenes of a lower density orthe medium density polyethylenes.

Although polyethylene containing one or more of the described additivesis particularly useful for improving the slip of products fabricated byextrusion into thin films, sheets, blown tubing, and the like, it mayalso be cast or molded into films, sheets, rods, tubes and piping,filaments, and other shaped articles, having better slip than similarproducts made of polyethylene containing no additive. In this regard,molded articles such as cups which tend to stick together when nestedare more readily separated when the polyethylene contains at least oneof the described additives. The polyethylene compositions of thisinvention may also be used for coating paper, cloth, wire, metal foil,glass fiber mats, synthetic and natural textiles, etc., where good slipis desired.

Polyethylene to which at least one of the additives is added hasimproved blocking properties, that is, film made from such polyethylenehas much less tendency to block than an identical polyethylenecontaining no addilive.

The following example illustrates the improved effect of the additiveson the slip of polyethylene sheet.

EXAMPLE 1 Two additives were introduced singly into a commercial highpressure process type polyethylene having a density of 0.92 and meltindex of 2 by introducing the additives into a commercial type Banburyand Banburying for 10 minutes at 190 F. The polyethylene was thensheeted on a roll mill, ground on a Wiley mill and screened through ascreen having 4 mm. openings and extruded into flat fiim on a 1-inchextruder equipped with a 6-inch fiat film die. The film was aged bysuspending in air at room temperature for at least 24 hours. The filmwas evaluated for slip by means of an inclined plane method, whichconsisted of stretching the film on an adjustable plane. A metal sledweighing grams was 2,991,263 3 4 placed on the film and one end of theplane then raised rate the spirit of this invention, they are intendedto be until the sled began to slide. The slope of the plane at includedwithin the scope of the appended claims. this point, expressed indegrees, was reported as the slip What is claimed is: of the additive.The following results were obtained: 1. A plastic composition comprisingpolyethylene and Table Slip Angle Additive Formula at Cone. of

0.05%, degrees I ll N,N-dioloyl adipamide-OMEN-*NIEL--(CHfir-CNH--O13H35 28 P i N-monooleyl adipamide-H1N(OHi)i-CNHC Ha5 23 Control (no additive) 36 The results clearly showthe improved slip character- 20 0.01% to 1.0% by weight of a member ofthe group istics of the polyethylene-additive compositions. Theconconsisting of N-oleyladipamide and N,N-dioleyladiptrol containing noadditive required an angle much highamide. er than thepolyethylene-additive compositions in order 2. A plastic compositioncomprising polyethylene and to cause the sled to slide. We have foundthat polyethfrom 0.01% to 1.0% by weight of N,N-dioleyladipylenecompositions which have a low film-to-metal c0- 25 amide. efficient offriction will also have a comparably low film- 3. A plastic compositioncomprising polyethylene and to-film coefficient of friction. from 0.01%to 1.0% by weight of N-monooleyladip- Various changes and modificationsof the invention can amide.

be made and, to the extent that such variations incorpo- No referencescited.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No,2,991,263 July 4, 1961 Clayton" F. Clark et a1.

pears in the above numbered pat- It is hereby certified that error ap dLetters Patent. should read as V ent requiring correction and that thesai corrected below.

Column 1, line 15, for 1858" read 1958 column 2, lines 55 and 56, for"Banbury and Banburying read banbury line 59, for "fiim" read film andbanburying Signed and sealed this 14th day of November 1961.

(SEAL) Attest: ERNEST W. WIDER DAVID L. LADD Commissioner of PatentsAttesting Officer USCOM M-DC-I

1. A PLASTIC COMPOSITION COMPRISING POLYETHYLENE AND 0.01% TO 1.0% BYWEIGHT OF A MEMBER OF THE GROUP CONSISTING OF N-OLEYLADIPAMIDE ANDN,N''-DIOLEYLADIPAMIDE.